Electric contact-point



UNITED STATES.

JOHN H. MULLER, OF SECANE, PENNSYLVANIA.

ELECTRIC CONTACT-POINT.

No Drawing.

7 '0 all whom it may concern:

Be it known that I, JOHN H. MULLER, a citizen of the United States of America, and a resident of Secane, in the county of Delaware and State of Pennsylvania, have invented a certain new and useful Improvement in Electric Contact-Points, of which the following is a true and exact description.

My invention relates to electric contact.

points or surfaces and is especially applicable to make and break circuits such as those used in magnetos, induction coils, etc. For severe service of this kind platinum has hitherto been the only material from which such points have been made, which gives really good service, and even platinum points are found in service to require filing at times to restore the bright metallic surfaces on which their most efficient action depends.

The object of my invention is to provide metallic contact points of an alloy which will in efficiency and durability compare favorably with platinum, which will be less costly and which will maintain bright metallic surfaces even under conditions under which platinum points become coated and require to bev scraped or filed to restore full efficiency, and my invention consists in a contact point formed of an alloy of gold and nickel in certain proportions and which I have discovered will produce such points having the highest efliciency in use and of remarkable durability and freedom from liability of such coating as impairs the efficiencyof such points.

The points with which I have obtained best results I form of an alloy containing approximately ninety per cent. gold and ten per cent. nickel, and the closer these proportions are adhered to the better service the points will give in use. I have found that the nickel may be used in as low percentage as eight per cent. with a corresponding increase in gold without material impairment in the qualities of the points other than that they are somewhat softer and not quite so durable in use, but below eight per cent. nickel the alloy loses hardness rapidly, and its lower melting point is also objectionable. Where the nickel is reduced to six per cent. the impairment of the alloy for my purposes is marked and points made from it will not give satisfactory results.

The effect of increasing the nickel percentage in the alloy above ten per cent. is not Specification of Letters Patent.

Patented Feb. 8, 1921.

Application filed December 23, 1918. Serial No. 268,055.

markedly injurious on the points up to a percentage of about twelve per cent. This increase in nickel results in greater hardness in the alloy and in a slight loss in conductivity both to heat and electricity. Above twelve per cent. nickel content the alloy is distinctly inferior for my purposes and really satisfactory points cannot, I have found, be made from an alloy havin a nickel content of over fifteen per cent. he purer the gold and nickel used in compounding my alloy the better, but such impurities as are usually found in the commercial metals, particularly in the nickel, are not markedly injurious, especially where a pure gold is used, as they form very small percentages in the alloy.

In my studies and experimentation on contact points of platinum and of alloys, intended to take the place of platinum, 1 have found the following qualities to be of great importance: The metal used must be of high conductiveness both to heat and electricity. The metal must have both hardness and toughness to withstand constant and rapid impact. The metal must be of such character as to retain a permanent bright metallic surface unaltered by heat or the vapors and gases to which it is exposed. The metal must have a comparatively high melting point, though this quality is somewhat interdependent with its conductivity to heat. The composition of the alloy must be such as to permit the constant passage of a small arc between the contact surfaces in the make and break action without it resulting either in the volatilization into the arc of sufficient material to wear away the surfaces or to prevent a sharp and complete break of contact by undue conductiveness of the vaporized material in the arc. All the above specified qualities are possessed in a high degree by my points made'for the described alloy of gold and nickel, and I be- I lieve them tobe in many respects better than platinum points, especially in producing efficient ignition at low. speed.

It is, I have found, important that car-- bon should not .be present in the alloy in appreciable quantity, and care should be taken that this substance is not present in the nickel in more than a fractional percentage, and that it should not be introduced in greater quantity in the compounding of the alloy. The percentage of copper, iron and cobalt ordinarily present in commercial nickel are not materially harmful in the alloy owing to their great dilution; but as V I have said,the purer the nickel usedthe' better is the character of the alloy for my purpose.

Having now described my invention, what I claim as new and desire to secure by Let-' ters Patent, is:

' 1. Electric contact points formed of an 10 alloy of gold and nickel containing nickel 2.. Electric contact points formed of an alloy of gold and nickel with the gold form 15 mg approximately ninety per cent. of the alloy and the nickel approximately ten per cent.

JOHN H. 

